Well completion apparatus and method



Oct. 15, 1968 w. A. PITTS ETAL WELL COMPLETION APPARATUS AND METHOD 7 Sheets- Sheet 1 Filed Feb. 18, 1966 K R. m 0 Z W HZ W Z 5 PL Oct. 15, 1968 Filed Feb. 18, 1966 W. A. PITTS ETAL WELL COMPLETION APPARATUS AND METHOD '7 Sheets-Sheet 4 ywim Jiv E4 W000 Pwrzglh.

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Oct. 15, 1968 w. A. PITTS ETAL 3,405,763

WELL COMPLETION APPARATUS AND METHOD Filed Feb. 18, 1966 7 Sheets-Sheet 5 ITTI W277i? l 0w; PM

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ORNEYS Oct. 15, 1968 w. T s ETAL 3,405,763

WELL COMPLETION APPARATUS AND METHOD Filed Feb. 18, l96 7 Sheets-Sheet 6 2 0 2 INVENTORS Wu 4 MM. l lrrs op A. PIERCE a. B L, ATTORNEYS 1968 w. A. PITTS ETAL WELL COMPLETION APPARATUS AND METHOD 7 Sheets- Sheet '7 Filed Feb. 18, 1966 ,0 ,a m a 2 M j w a s w W ///7'/ I T N NC. 0 I I 1 W i/m d I I -r z 5 4H I r R WA If u Z Z 0 M1. J W 4 4, i r 0 j 4 H 0 a A E 0 W? I d 7 7 F i m m j B /v .4, //IME////// w 4 4 IT M M a no G I m 4 84 AU 9/ a, w 0 44 MI I I} In. a /w n r m flJ Y m I).

United States Patent ice WELL COMPLETION APPARATUS AND METHOD William A. Pitts, Robert L. Grain, and Elwood K. Pierce,

Houston, Tex.; said Grain and said Pierce assignors to Gray Tool Company, Houston, Tex., a corporation of Texas Filed Feb. 18, 1966, Ser. No. 539,242 (Filed under Rule 470:) and 35 U.S.C. 118) 38 Claims. (Cl. 166-46) The present invention relates to an expansible ring-type casing hanger especially adapted for use in underwater completion work because it can be reliably set down hole from a location at the surface though not limited to down hole use, and also to apparatus for setting the novel hanger and a method for completing and/or abandoning wells.

It is an object of the invention to provide an expansible support ring-type casing hanger that possesses important advantages over swinging or sliding dog and slip type hangers inasmuch as it is self-expanding even under adverse conditions, is unitary and thus not subject to coming apart or sticking and which is less expensive to fabricate and use because of its Spartanness.

Another object of the invention is the provision of means for retaining the expansible support ring in a retracted condition during lowering thereof with a casing string into a petroleum well in order to protect the ring and outer well casing alike from abrasion, to prevent fouling of the ring on shoulders of other equipment or in tight places in the casing string and which allows the retracted ring to be lowered below its final setting position, for instance so that the hole bottom can be bumped with the lower end of the casing string.

A further object of the invention is the provision in apparatus of the type described of means for arming the retracted expansible support ring for expansion as the casing string and support ring are raised from the position below the final setting position.

Yet another object of this invention is the provision of apparatus of the character described which allows the casing string to be withdrawn from the well even after the expansible support ring has been armed for expansion.

A further object of the invention is the provision of apparatus for setting a plurality of expansible support rings, or combinations of packers and expansible support rings in tandem on the same casing string in order to transfer support at a plurality of substantially vertically spaced points.

It is an object of the invention to provide apparatus of the type described wherein the hung casing string can be severed, for instance by cutting or shooting off, below the support ring, so that the uncemented casing to be salvaged can be withdrawn from the hole without releasing the support ring.

A further object of the invention is the provision of a method for setting a down hole hanger which includes lowering the casing string and retracting the expansible support ring below the calculated setting depth; progressively lifting up and slacking off on the casing string in order to detect when the support ring engages its seat thus avoiding mistakes caused with conventional equipment when the drag caused by a tight hole is mistaken for hanger seating, then tautening the casing above the support ring from the surface to provide for thermal expansion.

It is another object of this invention to provide a support ring triggering pawl assembly that is reusable and will not be damaged as the casing string and support ring are being lowered and means for preventing the triggering pawl assembly from scoring or puncturing outer casing or from fouling on down hole equipment while being received and lowered in the well.

3,405,763 Patented Oct. 15, 1968 Further objects of the present invention include the provision of casing hanging means that provide maximum support in a minimum inter-casing annulus, for example 13% inch x 9% inch support ring-hanger assembly of the present invention will pass through a 13% inch O.D. casing hung in a 13% inch casing collar or housing which is in the casing string of the 13% inch O.D. casing.

A further important object of the present invention is the provision of means and a method for temporarily abandoning petroleum wells near the mud line so that formation definition wells can be drilled after which the temporarily abandoned wells can be tied back onto and completed if the wells turn out to be worth producing from, thus saving in the neighborhood of 20,000 dollars per well in navigational aids, installation costs and tied-up equipment costs.

These and further objects of the invention will become more clearly apparent, as will the principles and more of the scope of advantageous applicability of the present invention during the course of the following detailed discussion which primarily relates to preferred embodiments of the invention which are shown in the annexed drawings.

In the drawings:

FIGURE 1 is a fragmentary vertical sectional view, with parts in elevation, of an inner casing being hung in an outer casing via novel expansible ring casing hanger apparatus according to the present invention showing an early step in the setting procedure;

FIGURE 2 is a fragmentary elevation view of the expansible hanger ring and its locking and releasing device of FIGURE 1, drawn to an enlarged scale;

FIGURE 3 is a vertical radial sectional view taken substantially along line 33 of FIGURE 2;

FIGURES 4-8 are sectional views similar to FIGURE 1, except for the omission of the peripheral region of FIGURE 1, of successive stages in the setting procedure;

FIGURE 9a is a fragmentary vertical sectional view with parts in elevation of an exemplary petroleum well completed in accordance with principles of the present invention;

FIGURE 9b is a fragmentary vertical sectional view showing the lower portion of FIGURE 9a on a larger scale;

FIGURE 10 is a fragmentary vertical sectional view, with parts in elevation, of the well of FIGURE 9, temporarily abandoned in accordance with principles of the present invention;

FIGURE 11 is a fragmentary vertical sectional view, with parts in elevation, of a second exemplary petroleum well completed in accordance with principles of the present invention;

FIGURE 12 is a fragmentary vertical sectional view with parts in elevation, of the well of FIGURE 11 temporarily abandoned in accordance with principles of the present invention; and

FIGURE 13 is a somewhat schematic fragmentary vertical sectional view of a petroleum well having an inner casing hung at a plurality of vertically spaced points down hole in an outer casing via novel expansible ring casing hanger apparatus according to the present invention.

In FIGURE 1, the casing 10 represents a casing hanger housing that, with respect to the first hung casing can be the surface casing, and with respect to later casings, the previously hung next radially outer casing. The casing 10 is conventional except for having a circumferential, support ring landing groove 12 and a circumferential, pawl tripping groove 14 communicating with its central bore 16. The groove 12 is spaced vertically above the groove 14 in the inner peripheral surface 18 of the casing 10 and both open radially inwardly. The support ring landing groove 12 can be seen to be defined by a generally radially directed, annular, upwardly facing lower shoulder 20, a generally frusto-conical downwardly enlarging downwardly facing, upper annular surface 22 and a generally cylindrical, radially inwardly facing surface 24 which intersects the surfaces and 22 at its opposite axial ends. Actually as Will appear hereinafter it is not critical that the surfaces 22 and 24 have strict frusto-conical and cylindrical curvature in an analytical geometric sense, the important factors being the provision of an upper, downwardly facing, downwardly enlarging surface at the upper extent of the groove 12 and vertical spacing between the shoulder 20 and the surface 22.

The important feature of the preferred embodiment of the pawl tripping groove 14 is the provision of an upper, downwardly facing, generally radially directed annular shoulder 26.

According to the present invention the landing and tripping grooves 12, 14 can be located anywhere along the casing 10 string, for instance near the upper end thereof, at the mud line, or several hundred or thousand feet downhole.

Furthermore, more than one pair of grooves 12, 14, vertically spaced, may be provided along the casing 10 string.

After the casing 10 has been emplaced by conventional means which do not by themselves form a part of the present invention, drilling is recommenced until sufiicient hole has been made to accommodate a next radially inner string 28 of easing. In making up the string 28, by conventional techniques, a hanger body 30 is interposed in the string and the string run into the well through the bore of the casing 10.

In FIGURE 1, the illustrated hanger body 30 is seen to include a generally tubular body 32, thick walled in its mid-region and grooved along its radially outer surface 34 to provide a plurality of longitudinally extending, radially outwardly opening, arcuately spaced circulating flutes 36 for facilitating circulation of fluids such as drilling mud and cement axially past the hanger body 30 in the annulus 38. Ribs 39 are defined between the flutes 36. The hanger body 30 is shown secured to adjacent upper and lower sections of casing 40, 42 via interior threading 44 adjacent opposite ends of its longitudinal bore 46 through other forms of securement could be employed. Preferably, the maximum diameter of the hanger body 30 is slightly less than that of the bore of the casing 10 so the hanger body 30 acts to some extent as a casing centralizer as the casing string 28 is being run.

In FIGURES 1, 2 and 3, the hanger body 30 is seen as being girdled at its mid-section by a radially outwardly opening circumferential groove 48 which receives a radially expansible support ring 50. The ring 50 is axially split at 52 and is constructed of elastic hard metal or the like so as to be self-expanding from a forced radial contraction upon the removal of the contacting force. As best illustrated in FIGURE 1, the groove 48 is characterized by having an upper region 54 in which the radial depth of the groove is less than the radial thickness of the ring 50, a lower region 56 in which the radial depth of the groove (measured from the maximum outer diameter of the hanger body 30) is greater than the radial thickness of the support ring 50. Between the regions 54 and 56 is an upwardly enlarging, downwardly facing annular transitional surface 58. The groove 48 is delimited by an upper, downwardly facing annular, radially directed shoulder 60 and a lower, upwardly facing annular radially directed shoulder 62. In the preferred embodiment of the invention as illustrated a longitudinally elongated radially outwardly opening generally rectangular pocket 64 is formed in one of the ribs 39, the pocket 64 at its upper extent intersecting the groove 48 at the latters lower extent. The split support ring 50 is received in the groove 48 so as to have its two split ends 66, 68 lie axially above and longitudinally centrally of the pocket 64.

The pocket 64 is defined by a radially inner, radially 4 outwardly facing, generally planar back wall 70, and a bottom wall 72 and to opposed side walls 74 extending normally to the back wall 70.

For convenience in manufacture, the pocket is shown provided with a ledge 76 parallel to the back wall 70 and surrounding the periphery of the bottom and sides of the pocket, the ledge defining a recess which surrounds three facets of, but is not so radially deep as, the pooket 64.

The means for temporarily retaining the self-expansible support ring '50 in a retracted condition adjacent the surface 56 of the groove 48 while the'casing is being brought to emplacement at the desired location in the well are mounted in the pocket 64 and include a pair of generally vertically directed parallel retaining pins 78. The two pins 78 are shown being generally cylindrical in their upper region 80 to be received in two downwardly opening, vertically directed sockets 82 in the ring 50 near the ends 66, '68. In order to radially contract the ring so the pins 78 can be inserted, a pair of radially outwardly facing sockets 84 may be formed in the radially outer surface 86 of the ring 50 near the ends 66, 68 for receiving a two pronged ring contracting tool (not shown) whose design particularities do not form a part of the present invention.

As seen best in FIGURES 2 and 3, the pins enlarge and are squared-off in their lower region in order to provide upwardly facing stop shoulders 88 and fiat laterally-outermost sides 90 for slidingly guided engagement With the sidewalls 74 of the pocket 64. Near their lower ends 92, the pins 78 are horizontally bored to define a dog pin receiving socket 94 in each. The dog pin 96 which is received in the sockets 94 acts as a pivot pin for a pawl 98 which is received thereon via a horizontal bore 100 through the pawl 98 in its lower region.

In the preferred embodiment shown, the combined thickness of the two pins 78 in their lower regions and pawl 98 is approximately equal to the length of the dog pin 96 and only slightly less than the distance between the pocket side Walls 74 so that once the elements 78, 96, 98 have been slidingly assembled as shown and placed in the pocket no additional means for securement of the pins and pawl to the pin 96 is necessary. The assembly 78, 96, 98 is retained in the pocket 64 by a cover plate 102 secured in an overlying relation to the pocket after the assembly 78, 96, 98 has been emplaced. The cover plate 102 is seen being of sulficient width to span the pocket 64 yet be received in the recess 76 so as to have its radially outer surface generally flush with the radially outer sur face of the body 30 to which it is secured for instance by tack welding at 104.

It should now be noticed that the cover plate 102 is rectangularly apertured at 106 to a width slightly greater than and height somewhat shorter than that of the pawl 98 so that the pawl is partly protrudable from the pocket through the aperture. The inner surface of the cover plate is shown obliquely relieved at 107 just below the aperture 106 to ease the pawl out through and back from the aperture. To provide guiding for the upper region of the pins 78, a pin guide insert 108 is mounted on the body 30, the insert being a generally rectangular block about as thick in a radial direction as the pocket is deep and with tabs 110 at its lateral edges to facilitate its being secured, for instance by tack welding to the cover plate 102 and body 30. In FIGURES 2 and 3 the pin guide insert should be seen to have two parallel, vertically oriented cylindrical bores 112 which receive and slidingly guide the pins 78 to prevent splaying of the pins under the restorative force resident in the support ring 50 upon its being contracted for insertion of the pins 78 in the support ring sockets 82. The guiding action provided by the pin guide insert 108 also prevents such binding of the pins 78 in their lower region against the laterally innermost vertical sides 114 of the pawl as would prevent its desired arcuate rotatability about its pivot pin 96. The pin guide insert 108 is made as a separate part for manufacturing and assembly convenience, it could be formed integrally with the cover plate. Another observation which can profitably be made at this juncture, is that by virtue of the length of the lower region of the pins 78 and the pawl and of the pocket 64 relative to the length of the upper region of the pins 78 which are received in the support ring sockets 82, the assembly 78, 96, 98 are movable vertically downwardly from the FIGURES l-3 position downwardly in the pocket 64 sufiiciently to completely withdraw the pins 78 from the sockets 82 and thus allow the support ring to spring radially outwardly to its expanded, relaxed condition as will be more thoroughly discussed hereinafter.

Now paying greater attention to the details of the preferred configuration of the pawl 98, it can be seen best in FIGURE 3 that the pawl is generally tapered below its pivot pin so as to have an increasingly smaller frontto-back thickness in the region 120 proceeding toward its lower end. The tapered surface 122 allows the pawl to swing outwardly through the aperture 106 sutficiently to engage the tripping groove 14 in the casing (FIG- URE l) but engages the pocket back wall 70 before the pawl has rotated sufiiciently to put it in danger of being sheared off or rotated so that its upper region is presented downwardly. Provision for rotation of about 1020 degrees from vertical is suggested as adequate to provide sufficient, safe protrusion.

In its upper region, the pawl is seen to thicken by having its radially outer face proceed obliquely upwardly and outwardly in a radial thickness sense at 124 at an acute angle leftwardly with respect to the longitudinal axis of the pawl as seen in FIGURE 3, then upwardly and inwardly in a radial thickness sense at 126 at an acute angle rightwardly with respect to the longitudinal axis of the pawl as seen in FIGURE 3 proceeding to the upper, flat end 128 of the pawl extending generally normal to the longitudinal axis of the pawl as seen in FIGURE 3, thereby defining a blunt nose at 130 at the juncture of the surfaces 124 and 126 and a sharper nose at 132 at the juncture of the surfaces 126 and 128. Further details of the pawl assembly include a normally curved leaf spring 134 secured adjacent one end thereof to the rear of the pawl in a vertically extending, rearwardly opening recess 136 into which the spring 134 is deformed as the pawl nose 130 is pushed rearwardly as will be explained hereinafter. Sufiice it to say, that the spring 134 is arranged to urge the upper region of the pawl outwardly of the back surface of the pocket. The spring is secured to the pawl via a conventional securement assembly 138 such as a rivet, nut and bolt or the like.

With the just described structure in mind, the description of a well completion using apparatus and methods according to the principles of the present invention will now be continued, specific reference being made to FIG- URES 1 and 48.

While the hanger body is (as in FIGURE 1) above the point where the pawl engages in the pawl tripping groove 14, the casing string 28 can be moved up and down and turned angularly without danger of releasing the retaining pins from the support ring, and even if due to some inadvertence the support ring should be released for expansion prematurely during lowering no harm will result in most instances since the smooth radially outer surface of the ring will allow it to be urged downwardly past casing 10 couplings should any have to be crossed before the landing groove is reached.

In FIGURE 4, the casing string 28 has been lowered in the casing 10 to such an extent that the pawl 98 on the body 30 has passed and is below the pawl tripping groove 14. During this stage, the support ring is still in a radially contracted condition so that the OD. of the ring is smaller than the CD. of the hanger body 30. This is because the pawl is not caught on the pawl tripping groove when the pawl traverses the groove 14 in a downward direction. Therefore, the ring is protected as it is passed downwardly in the outer casing 10. The pawl is free to move in and out during lowering and cannot get out of position in front of the aperture due to the fact that the pins 78 are positioned as far upwardly as they can move (either because of their topping in the sockets 82, or the shoulders between the upper and lower regions of the retaining pins abutting the underside of the pin guide insert 108). The pawl 98 does not trip in the tripping groove during downward movement due to the bluntness of the nose 130. Instead, as the casing string 28 is lowered, the pawl 98 freely passes into and out of the support ring landing groove 12 and the pawl tripping groove, so that if he wishes to, the operator can lower the casing 28 until its lower end tags the bottom of the drilled hole providing a double check on hole depth.

As the casing string 28 is raised from the FIGURE 4 to the FIGURE 5 positions, the pawl 98 contacts and enters the pawl tripping groove 14. The nose 132 hangs on the upper, downwardly facing surface of the groove 14 stopping further upward movement of the pawl 98, dog pin 96 and retaining pins 78. Because the casing string 28 including the hanger body 30 and support ring 50 continue to move upwardly, the pocket 64 slides upwardly with respect to the assembly 78, 96, 98 thus pulling the retaining pins 78 from the support ring sockets 82 whereupon the support ring self-expands until its radially outer surface engages the radially inner surface of the casing 10 between the grooves 12 and 14 (FIGURE 5). Continued upward movement of the casing string 28 lifts the support ring 50 to a spot radially inward of the landing groove 12 whereupon the support ring 50 snaps into the landing groove 12.

At this point the casing 28 could be lowered and would be supported on the support ring 50, but from the surface of the well the operator may not know exactly when the ring 50 has snapped into the landing groove 12. Accordingly, because the upper extent of the landing groove is tapered at 22 as is the support ring 50 at 140, further continued upward movement of the casing string 28 will radially collapse the support ring (FIGURE 6) as it is squeezed into a smaller diameter bore than the groove 12. Also noteworthy is the fact that the pawl, as it is slid nearer the bottom of the pocket 64 by upward movement of the casing string 28, contacts the inclined rear surface 107 of the cover plate below the aperture 106 which, coacting with the inclined surface below the pawl nose 130, cams the pawl out of the groove 14 and back behind the cover plate so that the pawl 98 at this stage does not prevent further upward movement of the casing string 28 including the hanger body 30 even to complete withdrawal of the casing string 28 from the hole.

Upon lowering the casing string 28 once more, the sup port ring travels downwardly until it hangs on the landing groove. Further lowering causes the transition surface 58 to cam the ring further radially outwardly to the radial extremity of the landing groove 12. Then the surface 54 slides along the radially inner surface of the support ring 50 until the shoulder 60 abuts the top of the support ring thus transferring the weight of the casing string 28 from the lowering nipple (not shown) or similar equipment to the casing housing 10 via the support ring 50 (FIGURE 8).

The invention will be further understood having reference to FIGURE 9 which shows an exemplary completed underwater petroleum well 200 including a 20 inch x 13% inch x 9 /8 inch x 5 /2 inch casing program. Various stages of completing the well 200 will now be dis cussed.

A ZO-inch O.D. casing 202 is first driven into the underwater ground to a conventional depth for drive pipes (conductor pipes) in the particular region. The casing 202 has a hanger seating collar 204 interposed in it as well as a disconnectable connection 206. The collar 204 is generally tubular, being thicker radially inwardly in its midregion than the remainder of the casing 202 so as to define an annular, upwardly facing, upwardly enlarging generally frusto-conical shoulder or hanger seat 208 having an ID. of 17% inches.

The preferred disconnectable connection 206 shown includes a pair of opposed hubs 210, 212 having exterior frusto-conical clamp receiving wedging surfaces 214 and internal frusto-conical sealing ring receiving surfaces 216. An elastic hard metal defiectable lip annular sealing ring 218 received between the hubs 210, 212 is elastically deflected to sealing condition by tightening of the clamp 220 to draw the hubs 210, 212 axially toward one another. The general arrangement of the connection 206 and in particular the sealing ring 218 are more completely and exhaustively described in the commonly assigned US. patents to Watts et al., Nos. 2,766,829, 2,766,998, and 2,766,999 and to Watts No. 3,216,746 and in the commonly assigned application of Latham et a1. Ser. No.-

315,962 filed Oct. 14, 1963, now US. Patent No. 3,325,176. Suitable clamps are more fully discussed in the commonly assigned US. patent application of Watts et al. Ser. No. 128,174, filed July 31, 1961, now US. Patent 3,231,297, of Grain et al. Ser. No. 388,775, filed Aug. 11, 1964, and of Brown Ser. No. 396,641, filed Sept. 15, 1964, now US. Patent 3,307,862, as well as in the commonly assigned US. patent to Watts, 3,181,901.

As shown in FIGURE 9, the sealing ring 218 is secured to the hub 210 via retaining screws 222 which are mounted in tapped holes in the ring 218 radial rib 224 and in through the end surface 226 of the hub 210. The seating collar 204 and disconnectable connection 206 are positioned in the 20-inch casing string 202 at locations in the exemplary completion 200 such that when the casing 202 is driven to desired depth, the seating collar 204 is located about 21 feet below the mud line and the disconnectable connection 206 is about feet above the mud line.

A -inch blowout preventer with radially contractile annular packing (not shown) is installed on the upper end of the 20-inch O.D. mud riser 230 which leads to the surface from the connection 206. Suflicient hole is then drilled through and below the 20-inch O.D. casing 202 to receive the 13% inch O.D. casing 232 which prior to or concurrently with, being lowered into the well is assembled sequentially to a 20-inch x 13 /s-inch casing hanger 234, a hanger extension 236, a hanger landing sub- 238 and a 13%-inch O.D. casing riser 240. Preferably, the elements 234-240 are made up on a joint of the 13%-inch O.D. casing and tested for sealing, physical integrity and workability then set back in the derrick until the 13% -inch O.D. casing is run.

As can be seen in FIGURE 9, the upper end of the 13%-inch O.D. casing 232 next below the hanger 234 is secured to the hanger by means such as exterior threading on the casing 232 at 242 and interior threading at 244 at the lower end of the bore 246 of the hanger 234. Preferably, the connection 242, 244 is tack welded at 248 when there is any significant chance that accidental back off might otherwise occur during subsequent drilling and completion operations.

The hanger 234 has an exterior, downwardly facing, upwardly enlarging, generally frusto-conical seat 250, broached a plurality of angularly spaced generally vertically directed circulation permitting flutes 251 similar to the flutes 36 on the hanger body of FIGURES l-8. At the upper end of its bore 246 the hanger 234 is interiorly threaded to receive the threaded lower exterior of the hanger extension 236. This connection is made permanent by circumferential welding at 252. Above the weld 252 the extension 236 is ported with at least one and preferably a plurality of angularly spaced radially directed circulation ports 254 which communicate at their inner extreme with the central longitudinal bore 256 of the extension 236. The bore 256 is cylindrically relieved at 258, 260 above and below interior threads 262, all being above the ports 254.

The hanger landing sub or lift bushing 238 is exteriorly threaded at 264 complementarily with the threads 264, but through a longer axial distance. Near its upper extent, a radially outwardly directed, downwardly facing annular stop shoulder 266 is provided on the sub 238 to limit its threadable insertability into the casing hanger 234. The 13%-inch O.D. casing riser 240 is secured to the upper region of the landing sub 238 via external threading 268 on the lower end region of the riser 240 and complementary internal threading 270 in the bore 272 of the sub 238 near its upper'end. The connection at 266, 268 is preferably m'ade fast by tack' welding at 274 when there is any likelihood that the riser might back out of the sub during subsequent completion operations.

A plurality of circumferential resilient seals 276 are shown provided between the extention 226 and landing sub 238 especially near the upper and lower ends of their region of coextension'as well as above and below the circulation ports 254.?

The 13% OD. casing string made-up as just described is lowered until the hanger frusto-conical seat 250 engages and restson the hanger seating collar 204 frustoconical seat 208'. Accordingly, the l3%-inch casing is suspended about 21 feet below the mud line from the hanger 234. i 7

Conventional cement is next pumped into the well to fill the annulus between the 13% inch casing string and the hole using conventional equipment such as packers and/ or plugs and the like; the cement being circulated to the surface via the 20-inch casing-13% inch casing annulus 278. At the surface, conveniently where the casing riser 240 emerges through the rotary table, a mark is placed on the exterior of the casing riser 240.

Next, the casing riser 240 is rotated eight complete turns to the right thus rotating the landing sub 238 with respect to the hanger extension 236. This raises the casing riser 240 and landing sub 238 sufliciently, about four inches, to fully open the circulation .ports 254. The mark that has been made on the riser 240 facilitates a visual checking of the necessary rise. Preferably the casing riser 240 is rotated slowly under upward tension about equal to the weight of the casing riser 240 from the hanger 234 to the elevators in order to minimize the load on the landing sub 238 exterior threads 264 during rotation. Water and/or mud is then circulated down through the casing riser 240 bore, out the circulation ports 254 and up to the surface through the annulus 278 to clear the latter of cement from about the level of the ports 254 and upward. After that portion of the annulus 278 is clean, the circulating ports 254, are closed by rotating the 13%-inch O.D. casing riser 240 eight complete turns to the left, again doing the rotating slowly and under tension to prevent thread damage.

Subsequent to the cementing operation just described, the 20-inch O.D. casing riser is cut off at 280 just below the point where the 13%inch surface casing head 282 is to be installed.

An annular thick weldable plate 284 is slipped around the l3%-inc'h casing riser 240 and Welded to the riser 240 and 20-inch O.D. casing riser at 286 and 288. (Further means to center the 20-inch OD. and 13%-inch O.D. casing risers can be provided, such as a plurality (for instance four) centering screws 290 installed through holes 292 cut in the 20-inch O.D. casing riser before drilling for and running the 13% inch O.D. casing string. In such instance, the screws 290 are retracted during drilling to provide full clearance through the 20-inch O.D. casing riser, then run in to the depth shown after the13%-inch O.D. casing has been run, prior to cementing.)

The 13%-inch O.D. casing riser 240 is then cut off at 294, just above the stub 280 of the 20-inch O.D. casing riser and the casing head 282 secured in place. As shown, the lower end of thecasing head 282 longitudinal bore 296 is socketed to receive welding material 298 for securement of the casing head 282 to the l3%-inch O.D. casing riser 240 and 294. Other conventional securement means could be used than the welding just discussed.

A conventional l3%-inch I.D. blowout preventer stack (not shown) is installed on the upper end of the head 282 and drilling operations recommenced through and below the l3%-inch O..D. casing in preparation for running the 9%-inch O.D. casing string 300. At this point it is important to observe that the 20-inch x l3%-inch casing hanger 234 longitudinal bore 246 has formed therein a circumferential pawl tripping groove 14 and a circumferential casing landing groove 12 as exhaustively described above with respect to FIGURES 1-8.

The 9 /s-inch O.D. casing string 300 is made up to include casing 302 secured, for instance by threads near the end 304, to the lower end of a casing hanger body 30' which is in turn secured for instance by threads near its upper end to a hanger extension 234'. The latter as well as the casing hanger landing sub 238 and 9% OD. casing riser 240 but for being smaller in diameter, are identical to the hanger extension 234 casing hanger landing sub 238 and l3%-inch O.D. casing riser 240 and are similarly numeraled with single primes after numerals designating corresponding elements.

The casing hanger body 30 differs materially from the casing hanger body 30 only by having a circumferential pawl tripping groove 14 and a circumferential casing hanger landing groove 12 formed in its longitudinal bore 246 and by combining the groove 48 surfaces 54 and 58, as a single axially elongated, circumferential downwardly facing, upwardly enlarging frusto-conical surface 306. This latter difference is matched by having a complementarily curved, radially inner caniming surface 308 on the split, self-expanding support ring 50. So constituted, the 9-inch O.D. casing string 300 is lowered into the well with the support ring 50' retained in a retracted condition on the hanger body 30' radially adjacent the groove 48 surface 56' by support ring retaining pins 78, basically as shown in FIGURES l-3. The casing string 300 is lowered sufficiently (as in FIGURE 4) that upon raising a few inches or feet (as in FIGURE 5) the hanger body 30' pawl 98 engages in the -inch OD. x B y -inch O.D. casing hanger 234 pawl tripping groove 14 causing the pins 78 to be withdrawn from the sockets 82 and allowing the ring 50 to self-expand. Next the casing string 300 is again lowered until the ring 50 seats at 12 on the hanger 234 and the support ring 50' supports the 9%-inch O.D. casing string as shown in FIGURE 9 (as more fully described above in regard to FIGURE 8).

The 9 -inch O.D. casing string is then cemented with returns to the surface and the annulus 310 between the l3 -inch O.D. casing riser and the 9 ,inch O.D. casing riser about the hanger is washed clean by rotating the 9 }(g-l1'lCh O.D. casing riser from the surface sufficiently to expose the circulating ports 254' and circulating mud and/ or water down through the 9%-inch O.D. casing riser, out through the ports 254 and up the annulus 310 to the surface. The ports 254' are then reclosed by turning the 9%-inch casing riser eight complete turns to the right.

The precautions which are advisably taken with regard to preventing accidental backing-out of easing joints, pre venting thread damage, and observing the physical integrity of the casing hanger support ring 50' retaining and releasing and circulation port opening and closing assembly discussed regarding FIGURES 1-8 and the lowering, hanging and cementing the l3%-inch O.D. casing string should also be observed while lowering, hanging and setting the 9 -inch O.D. casing string 300.

After the 9 -inch O.D. casing string 300 is cemented a now conventional casing hanger 312 is installed on the frusto-conical annular seat 314 in the casing head 282 bore 296 around the Q-inch O.D. casing riser, the latter cut off above the hanger at 316 and a casing bonnet 318 installed. Preferred hangers 312 and bonnets 318 are shown and more fully completely described in the commonly assigned US. patent to Watts et al. 3,051,513 and the commonly assigned application of Watts et al., Serial No. 65,064 filed October 26, 1960. A casing head spool 320 is then installed on the upper end of the casing head 282 using securement means such as the sealing rings and clamps of the aforementioned US. patents to Watts et al. 2,766,829, 2,766,998 and 2,766,999. Alternatively a unitary multiple bowl or compact casing head (a term recognizable to those skilled in the art) could be used instead of a casing head 282 and spool 320 secured to one another.

Next an ll-inch blowout preventer stack (not shown) is installed on the spool 320 and drilling operations are continued through and below the 9%-inch O.D. casing string 300 in preparation for running the 5 -inch O.D. casing string 322. The latter is made up, tested, run and hung (including support ring 50" retention, self expansion and emplacement means) as described in relation to the casing string 300 but for the omission of circulation ports, since the annulus 324 is preferably not cemented to the surface. The retaining pins, pawl, cover plate and the like for the casing string 322 are not seen in FIGURE 9 because they are angularly displaced from the section viewing plane, illustrating that the casing including its down hole hanger assembly need not be angularly oriented since the support ring seating groove 12 and pawl tripping groove is circumferential. This is another decided advantage represented by the structure and method of the present invention. Other elements being the same as those described above relating to the 9%-inch O.D. casing except for being of smaller diameter, they are similarly numeraled in FIGURE 9 but for double primes.

A casing hanger 326 is then installed in the spool 320, the casing 322 hung with respect to the hanger 326, out off above the hanger 326 and a bonnet 328 installed. Further completion including installation of a tubing head 330, valves 332, bull plugs 334, clamps 336, 338 and a preventer stack (above the clamp 338, not shown) is conventional. It should be noted that the purpose of the hangers 312 and 326 is to support at the surface the weight of the portions of the respective casing strings which extend above the respective, novel down hole support ring casing hanger assemblies up to the surface.

With reference to FIGURE 10, should it become necessary or desirable to temporarily abandon the completed well shown in FIGURE 9, for instance to allow use of equipment on other formation definition wells in order to determine whether the first well is a fiuke, or is in an area which can be economically produced from, the surface well head including the l3%-inch O.D. casing head, the casing head spool and tubing head, the hangers 312 and 326, their respective bonnets and accompanying valves, clamps and the like shown in the upper region of FIG- URE 9 are stripped down and the various casing risers and landing subs secured thereto are backed out of their respective down-hole hanger extensions by rotating the down hole hangers to the right until they are free, then lifting them to the surface. This operation leaves the down hole hangers and the respective hung casings undisturbed. The disconnectable connection is then disconnected and the 20-inch O.D. riser removed and withdrawn to the surface. A blind hub abandonment cap 342 is lowered and installed using the disconnectable connector as shown in FIGURE 10 blocking the well at 344. As shown, the cap 342 is relatively rigidly thick and is generally disk shaped, also having a radially outer, lower flange 346. The latter includes an upwardly facing, downwardly enlarging frustoconical clamp receiving exterior wedging surface 348 by which the disconnectable connector urges the hard metal sealing ring 350 into elastic sealing engagement with the radially inner, frusto-conical sealing surfaces of the 20- inch casing and cap 342. Preferably, the ring 350 is preassembled to the cap 342 as shown, for instance by screws 352. The cap 342 is equipped at its center with a ball check 1 1" valve assembly 354 arranged to permit fluid pressure above a predetermined magnitude to escape from the well, While keeping sea water or thelike out of the well. A simple floating marker buoy 356 is shown secured to the cap 342 eye bolt 358 via a buoy line 360.

An important feature of the arrangement just discussed is that because the various casings are hung below the mud line and the cap 342 protrudes only a little over about 5 feet above the mud line, the temporarily abandoned well does not represent a navigation hazard, i.e. a submerged obstacle likely to be struck by unwary shipping. Therefore, elaborate and expensive sounding buoys, flashing lights, protective screens and the like which conventionally cost upwards of $20,000 per well can in most instances be dispensed with in favor of an inexpensive marker buoy to prevent ship anchor entanglement.

It should also be recognized as an advantage, that once it has been decided to produce from the temporarily abandoned well of FIGURE 10, it is an easy matter to tie back into the Well and recomplete it, reversing the step above outlined in regard to FIGURE 10.

Another petroleum well 370 having a 30 x 16 x 30% x 7 /s-inch O.D. casing program is shown completed in FIGURE 11 and temporarily abandoned in FIGURE 12 in order to illustrate the adaptability and versitility of the hanger assembly and method discussed in regard to FIG- URES 18 and to further point out other features according to the present invention.

With reference to FIGURE 11, the well 370 which is typically in the Gulf of Mexico is begun by driving the 30-inch O.D. casing (drive pipe) 372 into the Gulf floor until refusal and then cutting it off at about 374, 30 feet above the mean low Gulf surface. As shown, the pipe 372 has been previously provided with a simple, radially inwardly extending hanger 376 which becomes located approximately at the mud line and has an annular, upwardly enlarging frusto-conical seat 378.

Next a -inch blowout preventer with radially contractile packing (not shown) is installed on the upper end of the -inch drive pipe 372, for instance using a flanged hub welded on the drive pipe upper end and a disconnectable connector secured to the flanged hub and to the blowout preventer and drilling is commenced through and below the drive pipe 372 in preparation for running and hanging the 16-inch O.D. casing string 380.

After sufficient hole has been made for the 16-inch O.D. casing and preparation completed for running it, the 20-inch blowout preventer, its connector and the flanged hub are out free from the 30-inch CD. drive pipe 372 at 382. The 16 inch O.D. casing string is made up to include suflicient casing 384, secured as by tack welded threading at its upper end to a hanger 386 having circulating flutes 388 and a radially outer downwardly facing annular frusto-conical seat 390 as well as a support r-ing landing groove 12 and a pawl tripping groove 14 in its bore 392.

The hanger 386 also includes a generally tubular longitudinally upward extension 394 interiorly threaded at 396 near its upper end 398 for receiving a casing lowering nipple or releasing tool 400, for instance of the type more completely discussed in the commonly assigned application of Hynes et al., Serial No. 249,796, filed January 7, 1963. The lower end region of the releasing tool 400 is exteriorly threaded at 402 complementarily to the threading 396 and has external tapered seat and seal means at 404 for sealing against the internal, upwardly enlarging frusto-conically curved seat 406 on the extension 396 upper end.

The tool 400 is internally threaded or otherwise provided with securement means at 408 to receive the lower end of a riser 410 exteriorly threaded at 412 adjacent its lower end and threaded and track welded at 414 to the tool 400. The 16-inch O.D. casing string is lowered until the hanger 386 seats at 378 and then is cemented, the cement being circulated to above the ocean floor. Excess cement within the annulus 416 is washed out preferably by lowering a tubing string into the annulus 416 and flushing out the excess down to below the connection 396, 402 as shown. Alternatively, the flushing could be accomplished by making the releasing tool 40 out of the hanger extension 394, lifting the tool 400 slightly and circulating fluid down the tool 400 bore, out between the tool and hanger extension and up the annulus 416 until the excess cement has been displaced, then recoupling the tool 400 and hanger extension 394.

The first casing head housing 478 is positioned on top of the 30-inch O.D. drive pipe 372. This housing has a casing bowl 420 andseat 422 to receive slips 424 for supporting the 16-inch O,D. casing upper region. After installing this head, the requisite tension is taken on the 16-inch O.D. casing riser 410 and the slips 424 set. The casing riser 410 is now out off at 426 and the casing bonnet 428 installed over the 16-inch O.D. casing and welded to the casing at 430. The next spool 432 is installed over the 16-inch O.D. casing head housing 418. The spool 432 incorporates a bowl 434 to receive slip 436 for supporting the 10%-inch O.D. casing string 438. After installing this head, a suitable adapter (not shown) is used to make the connection of the spool 432 to the 20-inch radially contractile preventer previously used. With this assembly, drilling is continued, making the necessary hole for the 10% -inch O.D. casing.

When the hole has been completed for the 10%-inch O.D. casing, the string 438 is made up, run and cemented. The setting procedure for the hanger 30', 50 is described in the sequence FIGURES 1-8. Cement is circulated above the 10%-inch hanger 30' and it is necessary to flush the excess from the annulus between the 10%-inch O.D. casing and the 16-inch O.D. casing before continuing the operation.

For this part of the operation, no changes of equipment at the deck level is required as the preventer is full opening and will pass the necessary supporting devices for the 10%-inch O.D. casing.

The releasing tool 400 in the 16-inch x 10% -inch hanger 30 is equipped with a plurality of circulation ports 440 for the purpose of circulating the excess cement from the annulus 442 between the 10%-inch OD. and 16-inch O.D. casing strings. To operate this device the 10%-inch O.D. casing riser is rotated four complete turns to the right; this opens the circulating ports 440. Circulation is now established, washing out all of the excess cement above the 16-inch x 10% -inch casing hanger.

After the excess cement has been circulated from the annulus between the 16-inch O.D. casing and the 10%- inch O.D. casing, the 10% -inch O.D. casing riser is rotated to the left four complete turns, closing the circulating ports 440 in the 10% -inch hanger extension 394. The slips 436 are now emplaced for instance by dropping them through the 20-inch preventer and the required tension pulled on the 10%-inch casing string.

The 10%-inch O.D. casing riser is next cut oif at 444 and the annular preventer and adapter removed. The 16- inch x 10% -inch bonnet 446 is then installed and welded to the 10%-inch O.D. casing at 448. The 10% -inch casing head spool 450 is now installed and the 11 inch preventer stack (not shown) assembled above the head. This equipment is full bore and will pass the hanger required to suspend the 7%-inch casing string 452. The casing head spool 450 has a bowl 454 within it to receive the slips 456 required to support the 7 /6-II1Ch OaD. casing string 458.

With this arrangement, drilling is continued for the 7 inch 0D. or 7-inch O.D. production string 458. This casing is made up, run and cemented in'the conventional manner and the hanger setting procedure described in the sequence FIGURES 18 followed to emplace and expand the ring 50". It is not necessary to flush out cement from the casing annulus 460 between the 7%-inch and10%- inch casing strings as the cement is not circulated back to the 10% -inch by 7 /s-inCh hanger level. The 7%-inch casing is suspended at the well head in the conventional manner and the tubing head 462 and control equipment installed above the 7%-inch O.D. or 7-inch O.D. casing 458 for well completion or testing.

With the casing strings set and cemented, the well may be brought in for production testing.

In order to temporarily abandon the well 370 of FIG- URE 11, the well head is stripped and the 16 inch O.D., lO /4-inch OD. and 7 /s-inch O.D. casing risers rotated to the right to free the landing subs from the respective hanger extensions, whereupon the freed landing subs and casing risers are withdrawn from the well. Then a protective cover 464 is run through the 30-inch CD. drive pipe 372 to seat as shown in FIGURE 12.

The cover 464 is generally downwardly cup shaped, having guide fins 466 for engaging the radially inner surface of drive pipe during lowering and while positioned. The cover 464 has a built in lowering bushing at 468 and eye bolts 470 for aiding emplacement and withdrawal and providing a site for the attachment of a floating marker buoy as in FIGURE 10. The cover 464 is provided with a radially inwardly directed circumferential shoulder via which it rests on the upper end of the 16-inch O.D. hanger extension and sealing means 472 for circumferentially engaging the exterior of the 16-inch O.D. hanger extension to prevent ingress of sea water to the well.

After the cover 464 is in place, the 30-inch CD. drive pipe is cut off at 474 near the cover 464 so the temporarily abandoned well protrudes only about 5 feet above the ocean floor and in other than very shallow water, thus represents little or no hazard to navigation. To tie back into the well 370 the steps just outlined in regard to FIG- URE 12 are simply reversed, including connecting a riser back onto the drive pipe at 474 using any conventional means such as a welded on flanged hub, a disconnectable connector and sealing ring or merely a butt welded joint.

FIGURE 13 diagrammatically shows a modification wherein a first casing 480 is emplaced in the well and has two support ring landing groove 12-pawl tripping groove 14 pairs spaced a substantial distance from one another along the first casing 480, the lower pair being for instance 2,000 feet down hole and the upper pair being approximately at the mud line.

After drilling for the net casing string 482 of smaller diameter, the casing string 482 is made up so as to have two casing hanger bodies 30' interposed therein approximately as far from one another as the distance between the two groove pairs 12-14. Preferably the distance between the hanger bodies 30' is slightly greater than the distance between the groove pairs and accordingly as the support rings 50 are expanded and emplaced by following the procedure outlined with respect to FIGURES 1-8, part of the casing 482 weight is borne by the lower ring 50', part is borne by the upper ring 50' and the remainder is transferred by the slips 484 to the casing head 486 bowl 488. The cementing and remainder of the completion of the well may be conventional or as outlined in FIGURES 9 and 11 and the well can be temporarily abandoned and tied back into as in FIGURES and 12.

It should be apparent that the modification of FIG- URE 13 is quite useful in completing deep wells where the total casing weight is large since each hanger can be emplaced so as to carry only the casing Weight below it, with the casing weight above it being borne by upper hangers.

Having thus described the present invention, it will be apparent to those skilled in the art that it has broad utility and the exemplary embodiments shown and described are susceptible of much modification such as addition, deletion and substitution of structural elements such as clamps, lowering nipples and the like without departing from the inventions principles. Accordingly, the invention should be understood as encompassing all such modifications as are within the spirit and scope of the following claims.

We claim:

1. In well completion apparatus, a down-hole casing hanger assembly including: a generally tubular casing hanger body; an elastic hard metal support ring mounted on said hanger body; surface means on each said support ring and said hanger body, said surface means being engageable to support said hanger body on said support ring; said support ring being split so as to have two adjacent ends; means on said casing hanger body disengageably engageable with said support ring near said ends to radially constrict said support ring when engaged therewith to thereby impart self-expansibility to said support ring, said support ring being thereby arranged to expand upon disengagement of said engageable means from said support ring; and securement means on said casing hanger body adjacent the ends thereof for securably interposing said casing hanger body in a casing string intermediate the ends of the casing string.

2. The apparatus of claim 1 wherein the means on said casing hanger body disengageably engageable with said support ring include a pair of retaining pins; said retaining pins being mounted on said casing hanger body for movement with respect thereto from a first position Wherein the retaining pins are engaged with said support ring to a second position wherein the retaining pins are disengaged from said support ring.

3. The apparatus of claim 2 further including means defining an annular circumferential groove in said casing hanger body; said support ring when constricted lying in said groove and having an outer diameter no greater than the outer diameter of said casing hanger body immediately above and below said groove whereby said support ring is protected from damage while the casing string including said support ring in a constricted condition is run into a well.

4. The apparatus of claim 3 further including means defining a radially outwardly opening pocket in said casing hanger body immediately adjacent said groove, said retaining pins being mounted in said pocket for longitudinal sliding movement within said pocket between said first and second positions; said ring having means defining a longitudinally extending socket therein adjacent each of the two adjacent ends; said retaining pins projecting into said sockets when in said first position and being withdrawn from said sockets when in said second position.

5. The apparatus of claim 4 including means in said pocket for guiding said retaining pins from said first positron to said second position along parallel paths.

6. The apparatus of claim 5 wherein the guiding means in said pocket include two vertical opposite sidewalls of said pocket and two parallel laterally outermost surfaces on said retaining pins in sliding engagement with said two vertical opposite sidewalls.

7. The apparatus of claim 5 wherein the guiding means in said pocket include a pin guide insert rigidly mounted on said casing hanger body in said pocket, said insert having a means defining a pair of laterally spaced, vertically directed bores therethrough, said retaining pins projecting through said bores and the inner peripheral surfaces of said bores being closely complementarily configured with respect to at least the portions of the outer peripheral surfaces of said retaining pins which pass through said bores as said retaining pins move from the first position to the second position thereof.

8. The apparatus of claim 4 wherein said pocket is below and intersects said groove; said retaining pins projecting vertically upwardly and said sockets opening vertically downwardly.

9. The apparatus of claim 8 further including a pawl mounted on said casing hanger body and arranged to sense the reaching of the vicinity of a hanging provision in a well, said pawl being adapted to move said retaining pins from said first position to said second position upon such sensation.

v 10. The apparatus of claim 9 wherein the pawl is pivotally mounted in said pocket between said pins; said pawl having means defining a laterally directed bore therethrough; a dog pin slidably received in said pawl bore and the ends of said dog pin protruding from each end of said pawl bore; means defining lateral opening means in said retaining pins receiving said dog pin ends, the width of the assembly including said retaining pins, dog pin and pawl being approximately equal to the width of said pocket thereby ensuring an efilcient guidedly slidable fit of the last mentioned assembly in said pocket.

11. The apparatus of claim 9 further including: cover plate means mounted on said casing hanger body at the mouth of said pocket; said cover plate retaining said retaining pins and said pawl in said pocket; means defining an aperture through said cover plate, said pawl being pivotably protrudable from said pocket only through said cover plate aperture.

12. The apparatus of claim 11 wherein said pawl pivotably protrudes from said pocket through said aperture when said retaining pins are in said first position in order to be in position to receive said sensation and wherein said pawl is forced pivotably backwardly of said pocket and away from protrusion from the pocket through the aperture by the radially inner surface of said cover plate below said aperture as said retaining pins are moved toward said second position in order to restrict the pawl at least temporarily to the confines of said pocket.

13. The apparatus of claim 12 further including means defining a smooth lip on the radially inner surface of said cover plate at the bottom of said aperture and means defining a blunt radially outer face on said pawl whereby said pawl is not easily damaged by forcible retraction behind said cover plate.

14. The apparatus of claim 11 further including a back wall in said pocket and resilient means in said pocket between the back wall of said pocket and the radially inner surface of said pawl, said resilient means biasing said pawl away from said back wall and toward said cover plate.

15. The apparatus of claim 14 wherein the resilient means comprise a leaf spring mounted on said pawl.

16. The apparatus of claim 3 wherein said annular circumferential groove is of greater axial extent than said support ring and has a radially outwardly facing radially inner surface, the last-mentioned surface being generally frusto-conically curved in a downwardly facing, upwardly enlarging fashion at least in a region thereof spaced axially upwardly from said support ring when said support ring is constricted, said surface frusto-conically curved region being adapted to cam said support ring to a greater outer diameter than the self-expanded, unconstricted outer diameter of said support ring upon movement of said region relatively downwardly through said support ring in engagement with the radially inner surface of said support ring.

17. The apparatus of claim 16 wherein the radially inner surface of said support ring is complementarily curved with respect to said region.

.18. The apparatus of claim 1 further including means defining hanger supporting seat means on the inner peripheral surface of said tubular casing hanger body, the last-mentioned means adapted to receive and support a second casing hanger body.

19. The apparatus of claim 18 further including a second casing hanger body received radially within the first-mentioned casing hanger body; wherein the means adapted to receive and support a second casing hanger body comprise a radially inwardly opening groove in the inner peripheral surface of said first-mentioned casing hanger body, an expanded self expansible split, support ring received in the last-mentioned groove and having means thereon supporting said second casing hanger body; and easing depending from said second casing hanger body.

20. The apparatus of claim 1 further including casing secured to and depending from said casing hanger body, a second generally tubular casing hanger body secured to and depending from said casing; a second elastic hard metal support ring, said second support ring being'split so as to have two adjacent ends; means on said second casing hanger body disengageably engageable with said second support ring near said ends to radially constrict said second support ring when engaged therewith to thereby impart self-expansibility to said second support ling, said second support ring being thereby arranged to expand upon disengagement of said engageable means from said second support ring; and further casing secured to and depending from said second casing hanger body, whereby the weight of said casing and of said further casing is supportable at axially spaced points along the casing string.

21. The apparatus of claim 1 further including casing secured to and depending from said casing hanger body; a casing head having a longitudinal bore; a casing riser secured adjacent the upper end thereof to said casing head in said bore; a generally tubularlanding sub secured to the lower end of said casing riser; an axially upward generally tubular extension on said casing hanger body; cooperative means on said casing hanger body extension and on said landing sub for removably securing the landing sub to the extension in a partly overlapping relationship whereby the well in which said apparatus has been mounted can be temporarily abandoned by disconnecting the landing sub from the extension and removing the landing sub and casing riser casing head from the well.

22. The apparatus of claim 21 wherein said cooperative means comprise complementary threading on said landing sub and on said extension.

23. The apparatus of claim 21 further including cooperative stop means on said landing sub and on said extension engageable for limiting the extent of overlap of said landing sub and said extension; and means forming a circumferential, fluid tight seal between said landing sub and said extension when said cooperative stop means are engaged.

24. The apparatus of claim 23 further including means defining at least one radial circulation port in at least one of said landing sub and said extension in the overlapable region thereof; said circulation port being sealingly blocked when said cooperative stop means are engaged and said circulation port being open when said landing sub is substantially less overlapped with said extension than it is when said cooperative stop means are engaged.

25. In well completion apparatus: a first casing string mountable in a well and having means including a radially inner peripheral surface defining a longitudinal throughbore; means defining a radially inwardly opening support ring landing grove in said radially inner peripheral surface; means defining a radially inwardly opening pawl tripping groove in said radially inner peripheral surface subjacent said support ring landing groove; a generally tubular casing hanger body slidably receivable in said first casing string; an elastic hard metal support ring, said support ring being split so as to have two adjacent ends; means on said casing hanger body disengageably engageable with said support ring near said ends to radially constrict said support ring when engaged therewith to thereby impart self-expansibility to said support ring, said support ring being thereby arranged to expand upon disengagement of said engageable means from said support ring; pawl means mounted on said casing hanger body and arranged to engage in said pawl tripping groove, said pawl being adapted to disengage said engageable means from said support ring upon engaging in said pawl tripping groove, thereby self-expanding said support ring for seating on said support ring landing groove; said casing hanger body further including means engageable with said support ring after the selfexpansion of said support ring for supporting said casing hanger body on said support ring.

29. The apparatus of claim wherein said pawl has a generally radially outwardly and axially upwardly inclined radially outer face and means defining a groove engaging nose at the upper end of said pawl, said pawl being thereby arranged to traverse said pawl tripping groove in a downward direction and not engage in said pawl tripping groove and to engage in said pawl tripping groove only when moved upwardly with respect to said pawl tripping groove from a position at least as low as said pawl tripping groove.

30. In =well completion, a method which comprises: positioning a first casing string in a well; providing a support ring landing groove in said first casing string substantially down hole from the well surface; assembling a second casing string including a casing hanger body interposed therein; contracting an elastic, split, hard metal support ring about said casing hanger body at a first position on said casing hanger body; lowering said second casing string into and downwardly in said first casing string; sensing the proximity of said support ring to said support ring landing groove; releasing said support ring for self-expansion upon a sensation of close proximity of said support ring to said support ring landing groove, emplacing the support ring in said support ring landing groove; and supporting said second casing string via said casing hanger body on said support ring.

31. The method of claim which includes: providing a downwardly facing seat on said casing hanger body above the location of said support ring with respect to said casing hanger body when said support ring is in said first position; and wherein the steps of (a) emplacing the support ring in said support ring landing groove and (b) supporting said second casing string via said casing hanger body on said support ring include displacing said casing hanger body relatively downwardly with respect to said support ring and concurrently camming said support ring radially outwardly into concurrent engagement with said landing groove and said downwardly facing seat.

32. The method of claim 30 wherein the sensing step and the step of releasing said support ring for self-expansion upon a sensation of close proximity of said support ring to said support ring landing groove include: providing for said sensation at a fixed point on said first casing string near said support ring landing groove; and at a fixed point on said second casing string near said support ring; said sensation occurring only as the point of said second casing string radially coincides with the fixed point on said first casing string and the second casing string is being moved axially upwardly relative to said first casing string; lowering the second casing string sutficiently low that said point thereon is below said fixed point on said first casing string; then raising said second casing string at least until said point and said fixed point laterally coincide.

33. The method of claim 32 further including tagging the well bottom with the lower end of the second casing string during the step of lowering the second casing string sufliciently low that said point thereon is below said fixed point on said first casing string.

34. The [method of claim 32 wherein, in the step of raising said second casing string at least until said point and said fixed point laterally coincide, the second casing string is wholly withdrawn fro-m the well, thereby salvaging the entire second casing string.

35. The method of claim 30 wherein the well is under water comprising: providing a disconnectable joint in said second casing string above said support ring; circulating cement into the annulus between the first and second casing strings; establishing communication between the second casing string bore and said annulus proximate said disconnectable joint; circulating fluid down said second casing string, out the established communication and up the annulus to the well surface to ensure that excess cement is cleaned from the annulus and in particular to ensure the preservation of disconnectability of said disconnectable joint.

36. The method of claim 35 further including disjoining said second casing string at said disconnectable joint and withdrawing all of the second casing string above said disconnectable joint from the well; severing said first casing string at a point laterally adjacent said disconnectable joint and withdrawing the freed portion from the well; and securing an abandonment cap on the upper end of the first and second casing string portions remaining in the Well.

37. The method of claim 36 wherein the abandonment cap is located near the mud line, so that the well, as abandoned, does not represent a significant submerged obstacle hazard to navigation.

38. The method of claim 36 further including removing the abandonment cap, tying the freed portion of the first casing string back to the first casing string portion remaining in the Well; and tying the second casing string above said disconnectable joint back to the second casing string portion remaining in the well by rejoining said second casing string at said disconnectable joint.

References Cited UNITED STATES PATENTS 1,856,469 5/1932 Crowell 166214 2,297,044 9/1942 Barker et al. 1662l4 2,941,599 6/1960 Datfin 166214 2,991,835 7/1961 Schwab 166-214 3,105,556 10/1963 Raulins al66214 3,227,218 1/1966 Fisher et al. 106-208 JAMES A. LEPPINK, Primary Examiner. 

1. IN WELL COMPLETION APPARATUS, A DOWN-HOLE CASING HANGER ASSEMBLY INCLUDING: A GENERALLY TUBULAR CASING HANGER BODY; AN ELASTIC HARD METAL SUPPORT RING MOUNTED ON SAID HANGER BODY; SURFACE MEANS ON EACH SAID SUPPORT RING AND SAID HANGER BODY, SAID SURFACE MEANS BEING ENGAGEABLE TO SUPPORT SAID HANGER BODY ON SAID SUPPORT RING; SAID SUPPORT RING BEING SPLIT SO AS TO HAVE TWO ADJACENT ENDS; MEANS ON SAID CASING HANGER BODY DISENGAGEABLY ENGAGEABLE WITH SAID SUPPORT RING NEAR SAID ENDS TO RADIALLY CONSTRICT SAID SUPPORT RING WHEN ENGAGED THEREWITH TO THEREBY IMPART SELF-EXPANSIBILITY TO SAID SUPPORT RING, SAID SUPPORT RING BEING THEREBY ARRANGED TO EXPAND UPON DISENGAGEMENT OF SAID ENGAGEABLE MEANS FROM SAID SUPPORT RING; AND SECUREMENT MEANS ON SAID CASING HANGER BODY ADJACENT THE ENDS THEREOF FOR SECURABLY INTERPOSING SAID CASING HANGER BODY IN A CASING STRING INTERMEDIATE THE ENDS OF THE CASING STRING. 